A photocuring process with acrylate or epoxide is a rapid process consuming little energy at low process temperature and low costs, and, thus, it has been employed in various fields of industry including the optical field and the display field. However, a transparent polymer produced by the photocuring process with acrylate or epoxide has a low thermal resistance to yellowing due to non-existence of siloxane having a high thermal resistance to yellowing and an oxidation reaction of a hydrocarbon backbone constituting the polymer. The transparent polymer produced by the photocuring process with acrylate or epoxide is not applicable to the optical field and the display field as, for example, a LED encapsulant requiring a high thermal resistance to yellowing.
Although Korean Patent Publication No. 10-2010-0073847 describes an acrylate-adhesive resin composition and photocurable adhesive composition including the same, the photocurable adhesive composition does not have a high thermal resistance to yellowing.
Thus, there has been an increasing demand for a thermally resistant optical siloxane resin used for producing cured transparent siloxane having a siloxane bond with a high thermal resistance to yellowing.